Extensible ladder



May 27, 1958 K. e. HANSEN 2,836,336

EXTENSIBLE- LADDER Filed June 29, 1955 2 Sheets-Sheet 1 INVENTOR.

Kim/5m 6. fim/stw y 7, 1958 K, e. HANSEN 2,836,336

EXTENSIBLE LADDER Filed June 29, 1955 2 Sheets-Sheet 2 IrraPA/IYJ UnitedStates Patent EXTENSIBLE LADDER Kenneth G. Hansen, Sacramento, tl'alif.Application June 29, 1955, Serial No. 513,741 3 Claims. or. 22e-20) Theinvention relates to ladders, and, more particularly, to ladders mountedon fire escape balconies and capable of extending downwardly to theground in telescoping fashion.

Trespassers and other unauthorized persons are prevented from entry ontoa buildings fire escape system by the simple expedient of elevating thelowermost balcony to a location well above the reach of anyone and evenabove the reach of the usual ladder. In event of emergency, however, itis highly essential that persons in the bu lding attempting to reach thesafety of the ground be furnished safe and reliable access from thebalcony to the ground. Ladders of various kinds have long been used forthis purpose and, in general, have performed adequately. Quite often,however, rust and corrosion have rendered such ladders inoperative,ladders or" the lazy-tong type, for example, having been particularlysusceptible to such difiiculty. Still other ladders of the downwardlyprojectable kind frequently tend to pinch or otherwise to harm theperson of the user as by a crank handle on the ladder hitting the personas the handle rotates rapidly during the downward movement of theladder.

Furthermore, many types of fire escape ladders are extensible only in avertical direction, exemplified by the lazy tong and lacobs laddertypes, and are thus free to sway during use. The average person, andparticularly one under distress or condition of panic from fire, findsdifiiculty in descending these types of ladders.

Still other extensible ladders, when tripped, extend downwardly at ahigh rate'of speed, the sudden checking or halting of the ladder as itstrikes the ground or pavement below causing a severe shock to theladder and balcony parts and setting up undesirable stresses on theentire mechanism.

it is therefore an object of the invention to provide an extensibleladder which is relatively inexpensive to manufacture and install, andyet which possesses a high degree of reliability.

It is another object of the invention to provide an extensible ladderwhich can by the expedient of adding and adjusting modular lengthsections, span any vertical distance ordinarily encountered.

It is yet another object of the invention to provide an extensibleladder which can be installed for use in either a vertical or inclinedattitude and which, in either of such attitudes, provides a stable andstiff ladder which is easy to descend even under conditions of panic.

it is a further object of the invention to provide an extensible ladderwhich incorporates an adjustable braking mechanism nicely to check thespeed of descent of the ladder sections and which thus circumventsharmful shock as the ladder abuts the ground.

it is a still further object of the invention to provide an extensibleladder which is easily retracted and maintained in predeterminedretracted location until tripped by the user.

, 2,836,336 Patented May 27, 1958.

It is yet a further object of the invention to provide a generallyimproved extensible ladder.

Other objects, together with the foregoing, are attained in theembodiment described below and shown in the accompanying drawings inwhich:

Figure 1 is a side elevation of a typical ladder installation, theladder being shown in fully retracted position, and, in outline, infully extended position.

Figure 2 is a front elevation to an enlarged scale of the ladder inretracted position, the plane of view being indicated by the line 2-2 inFigure 1, a portion of the showing being broken away to reduce theextent of the figure.

Figure 3 is a perspective of a typical grouping of ladder sections inretracted position.

Figure 4 is an exploded perspective view showing the construction andmanner of interengagement of a plurality of ladder sections.

Figure 5 is a perspective of the ladders cranking, Windlass, braking andlocking mechanisms.

Figure 6 is a plan of the mechanisms shown in Figure 5, the braking andlocking mechanisms being shown in section.

Figure 7 is a section showing the manner of interengagement of theladder rails and the friction reducing spacers usable in certain typesof ladder installations, the plane of section being indicated by theline 7-7 in Figure 1.

While the extensible ladder of my invention is susceptible of numerousphysical embodiments, depending upon the particular environmentalsituation to be met, a considerable number of the herein shown anddescribed embodiments have been made and installed and have performed inan eminently satisfactory fashion.

Mounted on a fire escape balcony 12, aflixed to a building wall 13, isan extensible ladder 14 of my invention. The ladder is supported inposition as by a laterally disposed mounting bracket 16 bolted on thebalcony top rail 17, or by bolting to the balcony bottom rail 18, and isfurther supported and conveniently held in a tilted or inclined attitudeby a suitable bracing member 19, the bottom of the ladder extendingdownwardly through the customary well (not shown) in the balcony floorgrating. Ordinarily the ladder is in a fully retracted position, but,when the occasion arises, a user can by a simple motion cause the ladderquickly to extend, or telescope, or project downwardly to the ground 20thus enabling the user to escape.

The ladder comprises a plurality of co-operating sections 21. Threetypes of sections are ordinarily used, each type dilfering from theother in small but important features later to be described. Each of thetypes, however, has in common with the others certain structuralfeatures including a pair of elongated rails 22, conveniently fabricatedfrom galvanized iron or aluminum channels held in spaced parallelrelation by a series of rungs 23.

it is sometimes desirable to provide certain-of the rungs, for examplethe uppermost and lowermost rungs in each section, with bronze or otherfriction-reducing annular spacing rings 24, or rollers, mounted on theends of the rungs adjacent the rails. The rings 24 serve not only tospace and align the contiguous and overlapping rails, as appears mostclearly in Figure 7, but also to assist the sections in slidingrelatively to each other.

One distinct type or kind of section is an uppermost or top section 31surmounted at its upper end by a pair of truncated triangular plates 32,or gussets, mounted on the corresponding top ends of the pair of rails22 and bent inwardly to form a pair of co-planar mounting plates 33.Bolted to the upper surface of each of the mounting plates 33 is asleeve journal 34. Each journal is coaxially disof'a short length ofchain (no h aesasae projects laterally outwardly from each of thejournals, terminating at -e'ach;end in a pairof square lugs 37 and 38,respectively. V i

- "Thegleft-hand lug 37, as appears in Figures 5 and is adaptedto'receive a crank 41," the inner end of the crank arm ,42, having Easquare-shaped 'aperture 43 to accept the lug 37 and thus 'to rotate theWindlass shaft 36 2's the-crank-handle 44 is revolved; After the ladderis cranked to and loek'edin "fully retracted .positionthe crank ill-isordinarily removed from the lug 37 and allowed to 'dangle'fromtt'hebalcony rail bracket 16, or oither nearby but "outeof-the-way location,at the end With the removal of the crank in this fashion, the persontripping the ladder will'not be struck and harmed by the rotating crankas might be the caseiwerethe crank'allowed to remain onfthewindlassshaft. V I

Rotational movement of the Windlass 'sha'ft'36 is reflected in --atranslational motion of a cable .51 reaved about the shaft 36 andconfined to the central portion thereof by a pair of Spaced'radially'disposed flanges 52 mounted centrally of theshaft. Thelowermost or free endiof the'cable is conveniently "afiix'ed to a yoke53 mounted on the bottom ladder section, as is shown most clearly inFigure 2,. or securedto one of the rungs.

tip'on tripping the ladder when it is in fully retracted position,.itheweight of the ladder sections causes the movable "or 'slidablesections to descend, thus causing thelcable 51 to pay off from thewindlass, and theiwind fairly low rate of speed, under the 'gravitalforce exerted that the ladder sections will, for average lengths ofladder, fully extend in from 5 to 8 seconds and with a slight degree ofimpact but which is not harmful to the parts. The braking produces somevibration in the ladder, the vibration shaking loose grit etc. whichmight have collected during periods ofnon-use of the ladder and thuspermitting the ladder sections to slide over each other more easilyeven' after extended periods of non-use.

While the brake serves its purpose effectively during descent of theladder its 'retarding efiect is not imparted, to a like deg ee, duringthe considerably slower ascent or retraction of the ladder resultingfrom cranking of the Windlass into raised position. The brake, in otherwords, does not significantly increase the effort required to wind upthe ladder.

Upon reaching fully retracted position, the circular brake plate 56 isfurther utilized so as to co-operate 7 with n ladder locking andtripping mechanism 66. Piercforce exerted by the walls of the plateapertures 67 on ing the plate '56 at equal radii from the shaft axis 62is a plurality, of apertures 67,'each adapted to receive a tripping andlockingpin 68 projecting laterally from an arm 69 pivotally mounted toswing about a pin 71 secured to apla'te 72 mounted on the adjacentone'of' the journal sleeves 34. "The disposition of the arm 69 '7 l thetripping pin 63 has, therefore, a component acting upon them the lowertelescoping sections "very shortly would assume a high rate ofacceleration and, unless retarded 'or checked, the bottom section wouldstrike the ground with an undesirable shock. I have therefore provided anovel braking mechanism, generally designatedjby thenumeral 55 andcomprising an eccentric adjustable weight loading impressed on theWindlass shaft 36. A very satisfactory weight loading is achievedbyldetach'ably fmounting on 'a circular plate 56 on the 'lu'g 38,. as bya pair of bolts 57, a pair, conveniently, of

segmentally configured blocks 58' each provided with a a pairof'apertures 59 to receive the, bolts. 'Radial'adjusttnent'of the blocksSSis achieved by provision in f the plate'Sfi of a radial slot 61. Thebraking mechanism is ordinarily adjusted at the time of installation,experience 'indicating'the number .ofblocks and initial radialdisplacement to be used asa first approximation.

If the first setting produces inadequate braking, a greater radial throworan increase inblocks (weight) is indi-. cated. {In any event, it ispreferable to add blocks rather than toiincrease radial displacement toa location .where thej arcuate portions of the blocks extend radiallyoutplus, the. square of the distance between the two axes times thexmassof the blocks, it can be seen that a slight radial adjustment .isproductive of a significant change in the brakes moment ofin'ertia. r ia By suitable'adjustmentof the mass and throw of the blocks any desiredtranslational velocity of the ladder sections is obtainable. Tinpractice, and owing to the fi 0f the situation, the blocks areadjustedfso in a left-handbr rearward direction. This rearwardly actingforce multiplied by the moment arm gauged by thedist'ance between theplate 56 and the center of the pivot pin'71 exerts a substantial .eiiorton the lever arm e irc'ausing it to' swing toward the plate 56 and, ineffect, tightly forcing or jamming the pin' 68 into the plate.

As a consequence of this construction, a positive lock is'exert ed onthe plate, a lock which prevents the plate and the Windlass fromrotating in 'a ladder extending siderable jarringor vibration.

While being extremely cfiective' against accident-a1 dis j lodgement,the tripping mechanism is quickly and'easily brought into operation lbyvolun'tary effort of a user.

The lever arm is made long enough so that the users strength exertedagainst the free end 76 of the lever arm-69 in'a lefthan'd direction, asappears in Figure .6,

is effective-to dislodge or trip the pin 68 from the. ap'ere ture '67and thus to permit the Windlass to pay out the a cable and allowing theladder, sections to'd'esccnd.

:As heretofore mentioned, his only the sectionsrot-her than the fi'xedtop section 31 which extend and retract. Thernovable ladder sectionsaresomewhat different in construction from the top section 31 and arethemselves structurally classifiable into two different'types or kinds.

rested outwardly rather than inwardlyas does the top section 31. 1 Aladder section of thi's'kind is termed, for

convenience, a fac'eoutsection, and is designated by the o numeral 81;-It,-is important 'to note that the adjacent channellegs of thetopsection31'and the faceout section 81 aredisposed in an overlying orinterengaging relation and are adapted to slide with respect'to eachother.

The second type or kind of movable section comprises.

a pair of channel rails facing inwardly toward eac'h'oth'er.

' This type is termed a facein section and is designated by the numeral82. j In a fashion comparable to the overlap existing between thechannel legs of-the ,top s'ection' 3'1 7 a. and the faceout section 81,the adjacent channel legs of the faceout section 81 and the faceinsection 82 are disposed in an overlying and slidable relation.

It is to be observed that with one top section 31, an extensible ladderof any length can be assembled by utilizing alternating arrangements offaceout and facein sections. Customarily, the sections are manufacturedin modular lengths, for example six feet. The balcony height thereforegoverns hoW many movable sections are to be utilized in any giveninstallation. The ladder shown in Figure 3, consequently, being foursections in length, would be twenty-four feet long, reduced by theamount of overlap 35, as shown in Figure 1. Usually, the artisaninstalling the ladder can, by appropriately tilting the ladder cause thebottom of the lowest section lightly to touch the ground in its fullyextended position. At other times, the tilt is adjusted to a steeperangle so that the ladder is, in effect, shortened by the distancebetween adjacent rungs so that two rungs in the bottom and next tobottom section are in registry.

In either event, the ladder is ordinarily assembled by supporting thetop section 31 in a horizontal attitude, rear side down, and by slidinginto longitudinal interengagement with the top section 3?. a faceoutsection 81, in the fashion indicated most clearly by Figure 4 when thefigure is viewed from the left-hand side of the drawing. In the eventspacer rings are not used, very satisfactory spacing is attained as aconsequence of the diameter adjustment or positioning of the ladderrungs, or by appropriate dimensioning and positioning of a group oflimit stop and pickup members mounted on the sections and now to bedescribed.

The first type of stop member is mounted adjacent to but spaced slightlyupwardly from the bottom of each section having its channel rails facinginwardly, as exemplified by the top section 31 and the facein sections82. This first type of stop member is located on the outer surface ofLhe right-hand channel leg, as appears in Figures 3 and 4- and istermed, for convenience, a lower stop plate 86.

A comparable but oppositely facing upper stop plate 87 is mounted on theleft-hand channel leg, adjacent the top of the leg, of each of thefacein sections 82. The plate 87 is slidable past the plate 86, therebeing no interference between the plates as one moves past the other asthe sections move.

On the outwardly facing surfaces of the channel webs of each or" thefaceout type of ladder sections 81 is a lower stop block 88, mounted atthe bottom of the section, and an upper stop block 8% secured byfastenings 91 at a location above and in abutment with the adjacentupper stop plate when the sections are in retracted position. Duringassembly, the upper stop blocks 3% are mounted after the various laddersections are translated into their interengaging relation. Since theupper blocks 89 interfere with the plates 86 in the same channel slot itis apparent that assembly of the faceout sections 81 onto the top ection31 and the facein section 82 could not be effected were the upper stopblocks 39 originally mounted on the sections 81. Reference to Figure 4from a left-hand direction most clearly illustrates this feature.

With especial reference to Figures 1, 2 and 3, the operation of theblocks becomes apparent. Assuming the locking mechanism to have beentripped by the user to an unlocked position, the weight of all themovable sections of the ladder begins to be felt. The movable sectionscommence to move downwardly, the "cable paying out and rotating theWindlass shaft so as to render operative the checking efiect of thebrake. Since the movable sections translate downwardly as a unit, Withina short time the upper block 89 of the adjacent section 31 abuts orstrikes against the lower stop plate 86 of the top ladder section 31.This abutment brings the first faceout section 81 to a halt but does notprevent the further downward movement of the balance of the" sections.Shortly, however, the upper stop plate 87 of the facein section 82strikes against the lower stop block 88 'at the bottom of the previouslyhalted section 81 and the section 82 is thereupon brought to a stop. Theoutboard, or lowest or most forward section, a faceout type of section8' as shown in Figures 1 and 3, still continues to telescope downwardly,however, until its upper stop block '89 hits against the interferringlower stop plate 86 of the adjacent facein section 82 and its motionthereby is halted. Substantially simultaneously the bottom of thesection strikes the ground and the ladder is in fully operativeposition.

When the emergency has passed, the crank handle is installed on the lug37 and the cable is wound onto the Windlass. The outboard or lowestsection commences first to retract, it being secured to the cable.Shortly, the lower block 88 of the outboard section urges upwardlyagainst the adjacent lower plate 86 and raises the facein section 82.This is soon followed by an upward urgency of the upper stop plate 87 ofthe facein section 82 against the adjacent upper block 89 of the faceoutsection 81, it being noted that the plates in the same channel do notinterfere with each other but that the blocks do interfere with theplates located in the same U-shaped channel.

As winding proceeds, the movable sections are pulled upwardly and in duecourse reach the position indicated by Figure 3, the movable sectionseach being in register and located slightly below the top section 31.Shortly, however, as winding continues, the upper surface of the stopblock 83 is brought into abutment with the lower surface of the stopplate 86 on the top section 31 and the movable sections are brought to ahalt. At this juncture the pin 68 can be swung laterally into one of theapertures 67, a sufiicient number of apertures being provided to receivethe pin Without the necessity of backing off the movable sections morethan an inch or two in any case.

it should be noted that the plates and blocks not only serve as spacersand guides keeping the sections in parallel alignment, and as appearsmost clearly in Figure 3, but they also serve as limit stop membersduring descent and as pickup members during retraction of the ladder.Furthermore, and as can be observed in Figure l, the plates and blocksare so proportioned that when the ladder is in fully extended positionthe adjacent sections are overlapped by an amount greater than thelongitudinal distance between rungs and so that the overlapping rungsare in register. Not only is rigidity thereby obtained but the usersfoot steps on the registering rungs simultaneously, giving an even moresecure footing.

It can therefore be seen that the device of my invention not onlyprovides a rigid telescoping type of ladder eminently useful to personsunder conditions of panic, owing to the familiarity of most people withladders of the rigid type, as distinguished from ladders of theflexible, swaying kind, but it also furnishes a unique and highly usefulpositive locking mechanism which can be quickly tripped and whosestructure is integrated with a simple yet highly efiicient ladder brakesystem.

What is claimed is:

1. An extensible ladder comprising: a top section mounted on a fireescape balcony, said top section including a pair of spaced longitudinalchannels facing toward each other, a plurality of transverse rungsextending between said channels, a pair of gusset plates mounted on theupper ends of said channels, a pair of coaxially disposed sleevebearings on said gusset plates, a shaft journaled in said bearings andterminating at each end in a lug square in section, a circular platemounted on one of said lugs, said plate having a radially adjustableweight eccentrically mounted thereon, a crank detachably mounted on theother of said lugs adapted to rotate said shaft and said plate, atripping bar pivotally mounted on one of said sleeve bearings adjacentsaid plate, said sesame tripping bartering a tripping pin normallydisposed thereon to engage one of a plurality of circumferentialapertures in said circular plate and to hold said plate and said shaftin predetermined position, a flexible cable secured at one end to theeentral'portion of said shaft,

a pair of cable confining flanges adjacent said sleeve bearings tomaintain the windings of said cable in the central portion of saidshaft, and a. lower stop plate mounted on the outer surface of -one legof each of said channels near thelower end thereof; a lower sectioncomprising a pair of channels, the corresponding legs of each or saidlower section channels lying in overlapping and sliding relation withthe adjacent legs of each of said top section channels, a pair of lowerstop blocks mounted at the lower ends of said channels, a pair of upperstop blocks mounted adjacent "the upper ends of said channels, a

a plurality of transverse rungs extending between said pair a ofchannels, said rungs of said lower section being in register with saidrungs of said top section as said lower *of said stop plates are inabutment with said lower of said stop blocks and means for securing theother end "of said cableto said lower section,said lower section beingmovable from a first position wherein said lower stop plate and saidlower stop block are inabutrnent to a secend position wherein said lower-stop plate and said upper stop block are in abutment, said cable beingunwound from said shaft first position to said second position, saidshaft" concurrently being rotated as said cable unreels therefrom, saidlower section being also movable from said secondposition to said firstposition as said crank is rotated to wind said cable on said shaft; andmeans for 'securing said top section to the fire escape balcony.

2; An extensible ladder comprising: a plurality of ladder sections eachincluding a pair of spaced longitudif nal channels and a plurality ofspaced transverse, rungs extending between said channels, the adjacentlegs of each of said channels being disposed in alternatingly op- Vposed facing relation and in overlapping position for sliding engagementtherebetween, each of said sections further including at least one pairof limit stop members projecting transversely from, said'pair ofchannels and adapted to abut a corresponding pair of stop members on theadjacent pair or said channels when adjacent h s sections are in a firstf-ully retracted position and ina second fully-extended positionrelative to each other; a

ladder mounting bracketattachable to an elevated bal ony structure, saidbracket being secured to one offsaid ladder sections; a Windlassrotatably mounted on said bracket, said Windlass including a cablefastened to the most dis-' tant of said ladder sections from'said one ofsaid ladder sections; means for brakingsaid Windlass; and means forlocking said Windlass in fully retracted position of said laddersections. a 3. In an extensibledadder comprising a'plurality ofoverlapping relatively slidable ladder'sections provided with limitstops movable into abutment as said section's translate from a fullyretracted to a fully extended posiion and from a fully extended vto afully retracted posi:

tion, a Windlass, and a cable windable about said Windlass and securedto one ofsaid ladder sections, the combina tion of: a circular diskcoaxially mounted on said wind-s lass, said disk including a pluralityof peripherally dis posed apertures and a radially elongated slot; asegmentally configured weight member havingran arcuate marginsubstantially coincidental with the periphery of said disk, said weightmember including a pair of radially disposed apertures therein; a pairof detachable fasten-.-

ings engageable with said slot and said pair of apertures and adapted tomount said weightmember at a predetermined radial location on said disk;and a Windlass locking mechanism including a pivotally mounted lockingclever, a locking pin on said lever and swingable thereby toward andinto engagement with one of said plurality of peripheral disk apertures"and away from and out of-engageinent with said disk aperture.

Weinberg Aug. 15, 195 0

